The exponential growth of mobile subscribers requires substantial increase of network capacity. Currently, network congestion is problematic on many third generation (3G) networks in a number of markets throughout United States and the world. The congested network causes dropped or failed calls, lower data rates and slow response times. Concurrent with this problem of rapid growth of number of users, there has been a rapid uptake of Smartphone subscribers, such as iPhone, Android phone and Blackberry phone users.
Long-term evolution (LTE) system, which offers high peak data rates, low latency and improved system capacity, is adopted by many operators to address the capacity issue. In the LTE system, an evolved universal terrestrial radio access network (E-UTRAN) includes a plurality of evolved Node-Bs (eNBs) communicating with a plurality of mobile stations, referred as user equipment (UE), via LTE-Uu interface. The radio access network further connects with a core network (CN), which includes Mobility Management Entity (MME), Serving Gateway (S-GW), and Packet data Network Gateway (P-GW), to provide end-to-end services.
While LTE network increases system capacity, it is projected that LTE network may soon face capacity problems. In both traditional network and LTE, operators always prioritize real-time voice traffic over data traffic. Resources are held in reserve across the network for circuit-switched voice traffic. New wireless data network, such as 3G and LTE network, also optimizes support for large amount of data traffic, such as video conferencing. Such design, however, does not work well for applications with short, infrequent data sessions, such as chatty applications and keep alive messages. Many common applications such as news, weather, and social networking, periodically connect and disconnect to/from the network for updates. These applications contain small amount of user data while still require a large amount of signaling traffic to establish and tear down the session. It is estimated that with the growing number of Smartphone applications over the network, the signaling overhead outpaces the data traffic by 30% to 50%, if not higher. Therefore, using data network efficiently is essential to improve network capacity.
Besides improving network efficiency, maintaining quality of service (QoS) is an important area for the successful growth of wireless networks. Applications over the wireless network have various requirements in terms of delay, bandwidth and error rate that they desire for optimal performance or user experience. The LTE system has defined a set of QoS Class Identifier (QCI) values, each corresponding to characteristics of a service required. The goal of standardizing QCI values is to ensure that applications/services mapping to the same QCI receive the same minimum level of QoS in multi-vendor network deployments, as well as in roaming cases. In the access network, it is the responsibility of the eNBs to ensure the necessary QoS for a bearer over the radio interface. Each bearer has an associated QCI, and Allocation and Retention Priority (ARP).
Traditionally, one application associates with one QoS because it has a predefined QoS requirement. Unlike traditional applications, for today's popular interactive applications, the QoS requirement is dynamic in nature. Many Smartphone applications generate traffic regularly even when the Smartphone is in background mode, such as when the user is not actively using the device. It is, therefore, desirable to have different QoS associates with one application. For example, the system can associate one QoS with a running application when the user is in interactive mode, and lower the QoS requirement when the user is not using the device. Such dynamic QoS scheme allows the system to reduce resource usage for the background applications, resulting in lower core network signaling overhead and improved LTE-Uu efficiency. On the UE side, it lowers the UE power consumption, primarily by allowing UE to use sleep cycles to greater extent, where hardware can be turned off or in standby mode. Usage of long sleep cycles or long DRX affects the QoS performance by introducing additional latency.
In addition to rapidly increased data and signaling volume that puts pressure on LTE-Uu interface, the amount of signaling to the Core Network is also a major concern of the operators. Operators have strong hope that LTE will efficiently support real “always-on”, which enables application updates. Such feature may lead to most UEs being in connected mode, which is quite different from today's wireless network. Especially for Smartphone, operators need to keep the core network load in control. The majority overhead in the Core Network signaling is due to initial connection establishments. We note also that while keeping a UE always in connected mode reduces the signaling needed for connection setup, it would generates instead additional signaling for handover, and furthermore using long DRX in connected mode for good battery consumption comes with the drawback of bad handover performance, due to low UE measurement periodicity of neighbor cells in long DRX. Thus, the problem of controlling and optimizing network signaling, resource usage and UE battery consumption for typical smart phones is complex. To reduce the overhead of initial setup, the network could be assisted in identifying “tricky” UEs, which utilizes “always-on” services, is moving, and frequently switches between Idle and connected modes. An efficient way of identify such UE enables operator to apply special algorithms with high complexity to such UEs to reduce the Core Network traffic, while applying simpler algorithms to non-problematic UEs.
In light of the exploding growth of the amount of mobile data and various mobile applications, coupled with the wide adoption of LTE by wireless network operators, it becomes important to find ways to improve network efficiency and to maintain the QoS of various applications. The embodiments of the present invention address various areas such as improving LTE-Uu interface efficiency, lowering Core Network signaling overhead and lower UE battery consumption.